This story shows how to frame a wall perpendicular or parallel to the ceiling joists.
When you add a wall in your house, it will either run perpendicular or parallel to the ceiling joists. Perpendicular construction is easier because you have built-in attachment points for the top plate where it crosses each joist. Parallel construction involves a bit more work because you'll need to add blocking between the joists. Shifting the wall so it's directly under a joist eliminates the blocking, but make sure you can live with that location instead of choosing it simply to save work.
Building the wall on the floor is the most efficient procedure, but space limitations may force you to build the wall in place. To do that, plumb the top and bottom plates to each other, and fasten the studs to the plates by toenailing (driving fasteners at an angle).
If you have a helper, allow at least one hour for a simple 8-foot-long wall that runs perpendicular to the joists. Framing openings such as doorways or windows will add time to the project.
Tape measure, stud finder, chalk line, plumb bob with nylon line, hammer or power screwdriver, level, circular saw
Measuring; snapping a chalk line; crosscutting; driving fasteners; using a stud finder, plumb bob, level
Draw project plans and locate joists.
2x4 studs, 2x4 top and bottom plates, 16d (3-1/2-inch) nails or 3-1/2-inch screws, tapered shims
Place the studs on edge between the plates. If any studs are not perfectly flat, turn them so that any slight gap is at the bottom. Hold them in position one by one and nail them in place through the plates. Make sure the edges of the studs are flush with the edges of the plates.
Dangle a plumb bob from the end and side of the ceiling plate to transfer the wall location to the floor. If you are working alone, hang the plumb bob from a nail in the plate. Repeat at the other end. This job is quicker with two people: One holds the string, the other marks the spot.
Anchor the wall by nailing up through the top plate into the ceiling plate. Make sure the edges of the two plates are flush. To protect a plaster ceiling, install the plate with 2-1/2-inch-long drywall screws. Check the wall for plumb with a carpenter's level, then nail the bottom plate to the floor.
Use a handsaw or reciprocating saw to cut away the ceiling flush to the inside faces of the joists where the wall will attach. Snap a chalk line along the center of each joist, then use a utility knife to cut away a 3/4-inch-wide strip of drywall. This exposes a surface on the joist onto which you can attach the new drywall.